Primary ATL patient samples are characterized by a high rate of STAT3 mutations and a strong correlation between STAT3 and Pim1. (A). Correlation of STAT3 and Pim1 in ATL patients. Real-time PCR analysis of STAT3 (red) and Pim1 (steel blue) expression in primary ATL patients (n = 48). Statistical analysis was carried out using Spearman’s correlation coefficient. Corresponding P values and linear regression values are indicated. GAPDH amplification served as an internal control. Mutational status of the STAT3 hotspot region is indicated below the corresponding patient. *, mutated; WT, wild-type; NA, not available. (B) Illustration of the STAT3 protein indicating the SH2 domain where frequent ATL STAT3 mutations were found. (C) A representational example of STAT3 mutations found in individual ATL patients. Arrows highlight the specific point mutation in the sequence, with the corresponding nucleotide change below. (D) Primary ATL patients have a 25.5% percentage of STAT3 mutations. Table demonstrating individual STAT3 mutations found in ATL patients. The consequence of each mutation, if known, is highlighted. UN, unknown.